Furnace burner for combusting solid particulate fuel

ABSTRACT

A furnace burner for combusting solid particulate fuel comprises a drum configured for containing the solid particulate fuel for combustion. The drum is supported in a burn chamber of a furnace for rotation about a substantially horizontal axis. The drum comprises a combustion portion inside the burn chamber and configured to support combustion of the fuel therein and a drive portion connected to the combustion portion and extending therefrom to an external end disposed outside the burn chamber for operative coupling to a drive system to rotate the drum. The combustion portion is perforated to permit passage of air but not fuel through a peripheral wall of the combustion portion, and comprises one or more interior flights extending axially and angularly of the drum in a manner conducive of movement of the particulate fuel, upon rotation of the drum, towards a downstream end to release fuel consumed during combustion.

This application claims the benefit under 35 U.S.C. 119(e) of U.S. provisional application Ser. No. 63/347,159 filed May 31, 2022.

FIELD OF THE INVENTION

The present invention relates generally to a furnace burner for combusting solid particulate fuel, and more particularly to such a burner comprising a rotary drum.

BACKGROUND

Conventional designs of furnace burner for combusting solid particulate fuel to generate heat in a furnace are respectively suited to specific types of solid particulate fuel, whether wood chips, pellets, agricultural screenings, coal or other solid particulate biomass or fossil fuel.

Each fuel has a distinct set of challenges for complete combustion, such as bridging of fuel, sticking, fusing together and different oxygen intake and location of admittance such as above and/or below the fuel during combustion.

Breaking up the fuel as it begins to stick, melt or clump together is a particularly difficult one of the challenges. Without breaking up the fuel, complete combustion is hard to achieve, resulting in inefficient combustion.

Also, ash, generated as a by-product of combustion of specific types of solid fuel, causes difficulties when trying to automatically remove the waste. Difficult fuels such as coal and certain agricultural screenings can leave behind large clinkers and chunks that become hard for automated systems to remove.

There are a few burner styles such as pot burners, stoker burners, and walking floor burners that try to burn a variety of fuels. While they work well for certain fuels, difficult fuels create the problems described above. These burners fail to properly agitate the fuel, the burners will move the fuel from point A to B but will not break up the fuel as it starts to clump, melt and stick together. Also, these burners are limited in directionality of oxygen admissible for combustion. Additionally, once the fuel has been burned the waste is inconsistent in size and is difficult to remove.

SUMMARY OF THE INVENTION

According to an aspect of the invention there is provided a furnace burner for combusting solid particulate fuel, comprising:

-   -   a housing defining a burn chamber arranged for receiving the         solid particulate fuel for combustion thereof to generate         exhaust gas;     -   a drum supported in the burn chamber and configured for         containing the solid particulate fuel for combustion, wherein         the drum is supported for rotation about a substantially         horizontal axis;     -   wherein the drum comprises a combustion portion inside the burn         chamber and configured to support combustion of the fuel therein         and a drive portion connected to the combustion portion and         extending therefrom to an external end disposed outside the burn         chamber, wherein the drive portion is arranged for operative         coupling to a drive system configured to rotate the drum around         the axis;     -   wherein the drum extends axially from the external end         configured to receive the fuel to a downstream end configured to         release the fuel that has substantially combusted for disposal         to waste;     -   wherein each of the combustion portion and the drive portion of         the drum comprises a tubular peripheral wall encompassing the         axis, wherein the peripheral wall of the combustion portion         locates a plurality of openings configured to permit passage of         air but not the solid particulate fuel therethrough; and     -   wherein the combustion portion comprises one or more flights         disposed on an inner side of the peripheral wall, wherein the         one or more flights extend axially and angularly of the drum in         a manner conducive of movement of the solid particulate fuel         towards the downstream end upon rotation of the drum.

This arrangement acts to displace and agitate fuel under combustion, which is helpful to prevent clumping thereof and to clean the burn chamber.

Preferably, the openings in the peripheral wall of the combustion portion are distributed across the full circumference thereof.

Preferably, the peripheral wall of the drive portion is imperforate.

In the illustrated arrangement, the drive portion is sized diametrically smaller than the combustion portion. Preferably, when the furnace burner includes a fuel feeding system with a screw conveyor in coaxial alignment with the drum, wherein the screw conveyor comprises helical flighting, the drive portion of the drum is sized diametrically substantially equal to the helical flighting to receive the same.

In the illustrated arrangement, the drive portion is circular cylindrical in shape and the combustion portion is polygonal cylindrical in shape.

Preferably, the drum is rotatably supported at or adjacent each of the external and downstream ends and is free of rotational support therebetween.

Preferably, when the combustion portion is polygonal cylindrical in shape, the drum comprises one or more axially-outwardly projecting annular flanges supported on an outer side the peripheral wall of the combustion portion at or adjacent the downstream end of the drum, and the furnace burner further includes a plurality of rollers rotatably supported in the housing and arranged for rolling engagement with the one or more annular flanges at circumferentially spaced positions of the drum.

In the illustrated arrangement, the drive portion of the drum is received in a bushing supported by the housing.

Preferably, when the furnace burner includes a fuel feeding system with a screw conveyor in coaxial alignment with the drum, and the screw conveyor comprises helical flighting, the helical flighting extends into the drive portion.

Preferably, the housing is configured to provide an air gap around a full circumference of the drum.

In the illustrated arrangement, the peripheral wall of the combustion portion comprises an outer metallic wall and an inner wall of refractory material, wherein the inner wall of refractory material comprises a plurality of axially-extending sections arranged side-by-side in a circumferential direction of the drum.

According to another aspect of the invention there is provided a furnace for generating heat from combustion of solid particulate fuel, comprising:

-   -   a base arranged for resting on a support surface;     -   a housing supported on the base;     -   a burn chamber in the housing and arranged for receiving the         solid particulate fuel for combustion thereof to generate         exhaust gas;     -   an inlet in the housing in fluidic communication with the burn         chamber and configured for admitting air from an ambient         environment of the furnace into the burn chamber for the         combustion of the solid particulate fuel;     -   a heat exchanger supported in the housing outside the burn         chamber and in fluidic communication therewith to receive the         exhaust gas therefrom, wherein the heat exchanger is configured         for transferring heat from the exhaust gas to a heating medium         which acts to distribute the heat;     -   a flue in fluidic communication with the heat exchanger and         arranged for releasing the exhaust gas with the heat removed         therefrom to the ambient environment of the furnace;     -   a fan operatively carried by the housing at a spaced location         from the burn chamber and arranged to generate an airflow to         draw gas from the burn chamber and to the flue so as to define a         flow of gas through the furnace; and     -   a burner configured for combusting the solid particulate fuel,         wherein the burner comprises:         -   a drum supported in the burn chamber and configured for             containing the solid particulate fuel for combustion,             wherein the drum is supported for rotation about a             substantially horizontal axis;         -   wherein the drum comprises a combustion portion inside the             burn chamber and configured to support combustion of the             fuel therein and a drive portion connected to the combustion             portion and extending therefrom to an external end disposed             outside the burn chamber, wherein the drive portion is             arranged for operative coupling to a drive system configured             to rotate the drum around the axis;         -   wherein the drum extends axially from the external end             configured to receive the fuel to a downstream end             configured to release the fuel that has substantially             combusted for disposal to waste;         -   wherein each of the combustion portion and the drive portion             of the drum comprises a tubular peripheral wall encompassing             the axis, wherein the peripheral wall of the combustion             portion locates a plurality of openings configured to permit             passage of air but not the solid particulate fuel             therethrough; and         -   wherein the combustion portion comprises one or more flights             disposed on an inner side of the peripheral wall, wherein             the one or more flights extend axially and angularly of the             drum in a manner conducive of movement of the solid             particulate fuel towards the downstream end upon rotation of             the drum.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in conjunction with the accompanying drawings in which:

FIGS. 1 and 2 are perspective views of furnace with an arrangement of furnace burner according to the present invention;

FIG. 3 is a top plan view of the furnace of FIG. 1 ;

FIGS. 4 and 5 are cross-sectional views along lines 4-4 and 5-5 in FIG. 3 , respectively;

FIGS. 6 and 7 are perspective views from opposite ends of the arrangement of furnace burner in FIG. 1 ;

FIG. 8 is a top plan view of the furnace burner of FIG. 6 , with a fuel feeding system omitted for convenience of illustration;

FIG. 9 is a cross-sectional view along line 9-9 in FIG. 8 , but showing the fuel feeding system;

FIGS. 10 and 11 are cross-sectional views along line 10-10 and 11-11 in FIG. 8 , respectively;

FIG. 12 is an enlarged partial view of the area indicated at I in Figure and

FIG. 13 is an enlarged partial view of an upstream portion of the furnace burner of FIG. 6 , with the fuel feeding system omitted for convenience of illustration.

In the drawings like characters of reference indicate corresponding parts in the different figures.

DETAILED DESCRIPTION

With reference to the accompanying drawings, there is shown a furnace burner 20 for combusting solid particulate fuel to generate heat in a furnace 1, for example a boiler which uses water as a liquid heating medium for distribution of the generated heat.

Turning initially to the furnace 1, and with reference to FIGS. 1 to 3 , the furnace 1 comprises a base 2 arranged for resting on a support surface, such as a building floor or a ground surface, and a housing 4 supported on the base 2 and forming an interior space for containing at least some constituent components of the furnace. In the illustrated arrangement, the base 2 comprises a series of elongated linear members 5 arranged to form a framework laid on the support surface, and the furnace housing 4 comprises a plurality of walls or panels 4A supported by at least a portion of the framework to form and arranged to form an enclosed structure standing upwardly therefrom.

As shown more clearly in FIGS. 4 and 5 , the furnace 1 includes a burn chamber 7 in the housing 4 and arranged for receiving the solid particulate fuel for combustion thereof to generate exhaust gas. In the illustrated arrangement, there is a removable burner assembly 20 that defines the burn chamber 7.

To provide oxygen for combustion of the fuel, the furnace 1 generally comprises an inlet 9 in the housing 4 in fluidic communication with the burn chamber 7 and configured for admitting air from an ambient environment of the furnace into the burn chamber. As such, the inlet 9 is provided in an exterior portion of the housing 4 so as to be in fluidic communication with the ambient or external environment of the furnace.

Furthermore, the furnace 1 includes a heat exchanger 12 supported in the housing 4 outside the burn chamber 7 and in fluidic communication therewith to receive the exhaust gas therefrom. The heat exchanger 12 is configured for transferring heat from the exhaust gas to a heating medium which acts to distribute the heat. Thus, passing through the heat exchanger 12 causes heat to be removed from the exhaust gas. In the illustrated arrangement, the heat exchanger 12 is of a type adapted for water as the heating medium.

Yet further, the furnace 1 includes a flue 14 in fluidic communication with the heat exchanger 12 and arranged for releasing the exhaust gas with the heat removed therefrom to the ambient environment of the furnace.

Moreover, the furnace 1 includes a fan 17 operatively carried by the housing 4 at a spaced location from the burn chamber 7 and arranged to generate an airflow to draw gas from the burn chamber and to the flue 14 so as to define a flow of gas through the furnace, which is shown in FIG. 4 using arrows following a path from the burn chamber 7 to the flue 14. As such, the fan 17 is located in downstream relation to the burn chamber 7, and in the illustrated arrangement, the fan 17 is also located downstream of all of the aforementioned constituent components of the furnace except for the flue which is downstream of the fan.

Since the burner 20 is in the form of a removable assembly, the burner 20 comprises a distinct housing 22, which is distinct from the furnace housing 4. The burner housing 22 is movable relative to the furnace housing 4, but in insertable therein in a working position of the burner, in which the burn chamber 7 is located inside the furnace housing 4, such that the exhaust gases from the combustion of the fuel are guidable through the furnace housing 4 to pass through the heat exchanger 12 to extract heat from the exhaust gases. In the working position, the burner housing 22 is operatively supported by and mounts to the furnace housing 4, so as to be unitary therewith in the working position.

To accommodate the removable burner 20, the furnace housing 4 of the illustrated arrangement comprises an interior burner chamber or compartment 23 arranged to receive the removable burner 20. The burner chamber 23 of the furnace housing 4 acts to locate the burn chamber 7, which in the illustrated arrangement is smaller than the burner compartment and occupies only a portion of a space or volume thereof. The burner chamber 23 of the furnace is open to an exterior of the housing 4 via an opening in an exterior one of the housing panels 4A to form a passageway therethrough for inserting and removing the burner 20. To facilitate fluidic communication of the exhaust gas generated in the burner 20, the burner compartment 23 is in fluidic communication with the heat exchanger 12.

Turning back to the burner, the burner housing 22 comprises an upstanding primary end wall or panel 24A to close, in the working position, the burner chamber 23 of the furnace 1 from the ambient environment. The burner housing 22 also comprises a tubular peripheral wall 24B connected in cantilevered relation to the end panel 24A, and an upstanding end wall 24C connected to the peripheral wall 24B in opposite relation to the primary panel 24B such that the peripheral wall is closed at its opposite ends. The burn chamber 7 is therefore substantially formed in a space delimited by the ends walls 24A, 24C and the peripheral wall 24B.

In the working position of the burner, the end wall 24C is located inside the housing 4, and the burner housing 22 is operatively supported by the furnace housing 4 by the primary wall 24A, which mounts to an exterior one of the panels 4A of the housing, typically that which defines the opening of the burner compartment 23, and by the end wall 24C which depends below the peripheral wall 24B to rest on the base 2 of the furnace.

Further to the housing 22, the burner 20 comprises a drum 25 supported in the burn chamber 7 and configured for containing the solid particulate fuel for combustion. The drum 25 is supported for rotation about a substantially horizontal axis R, meaning the axis R is oriented more horizontally than vertically, such that the drum rotates in an upstanding plane and there are upward and downward portions of the drum's rotary path. In the illustrated arrangement, the drum's axis R is horizontal.

More specifically, the drum 25 comprises a combustion portion 26 inside the burn chamber 7 and configured to support combustion of the fuel therein and a drive portion 28 connected to the combustion portion and extending therefrom to an external end 29 disposed outside the burn chamber 7, which is more clearly shown in FIG. 9 . As such, these two portions of the drum are longitudinal or axial sections of the drum. The drive portion 28 of the drum is arranged for operative coupling to a drive system 31 configured to rotate the drum around the rotational axis R, which is located externally of the burn chamber 7 and preferably externally of the furnace housing 4. Accordingly, the combustion portion 26 is wholly disposed inside the furnace housing 4. In contrast thereto, a partial length of the drive portion is disposed externally of the furnace housing 4; in the illustrated arrangement, the partial external length defining an external portion of the drive portion and according the drum is a minority length or depth portion, and a majority length or depth portion of the drum drive portion 28 is disposed inside the furnace housing 4.

The burner drum 25 extends axially from the external end 29, which is configured to receive the fuel, to a downstream end 34 defined by the combustion portion 26 and configured to release the fuel that has substantially combusted for disposal to waste. The external end 29 is defined by the drive portion 28 and can be considered to be an upstream end of the drum 25. Each of the upstream and downstream ends 29, 34 of the drum define openings for either admitting or releasing fuel.

As shown more clearly in FIGS. 4 and 5 , the furnace 1 additionally includes a spent fuel or ash removal assembly 36 in the form of a screw conveyor disposed below the drum 25 and adjacent to the downstream end 34 for transferring the ash out of the housing 4. Thus, the ash generated by combustion of the fuel is released by gravity, out the open downstream end 34 of the drum, and to the ash removal assembly 36.

With reference to FIGS. 9 and 10 , each of the combustion portion 26 and the drive portion 28 of the drum comprises a tubular peripheral wall encompassing the axis R, respectively indicated at 38 and 39. Since the combustion and drive portions are axial sections of a common drum, the peripheral walls 38, 39 are coaxial and encompass the axis R which is common and centered in relation to both portions indicated at 26, 28.

The peripheral wall 38 of the combustion portion 26 locates a plurality of openings 41 configured to permit passage of air but not the solid particulate fuel therethrough. Thus, gaseous oxygen (for example, in air) is admissible into the drum 25 for combustion of the fuel therein.

The oxygen for combustion is admitted into the burn chamber 7 by the inlet 9, which in the illustrated arrangement is disposed below the drum 25. Furthermore, in the illustrated arrangement, the inlet 9 is formed in the burner housing 22, and more specifically in the primary panel 24A.

To not restrict admittance of oxygen for combustion, the openings 41 in the peripheral wall 38 of the combustion portion are distributed across the full circumference thereof, and in the illustrated arrangement, also across the full length or depth of the combustion portion 26.

In conjunction therewith, the burner housing 22 is configured to provide an air gap around a full circumference of the drum. In the illustrated arrangement, this is achieved by the peripheral wall 24B which acts as a duct from the inlet 9 to the combustion portion 26. Thus, even though the inlet 9 is disposed below the drum 25, the ambient air admitted thereby is guided around the full circumference of the drum for circumferentially omnidirectional admission into the interior of the drum.

To displace and agitate fuel, the combustion portion 26 comprises one or more flights 44, and preferably plural flights, disposed on an inner side 38A of the peripheral wall 38. The flights 44 extend axially and angularly of the drum in a manner conducive of movement of the solid particulate fuel towards the downstream end upon rotation of the drum. That is, the flights 44, which in the illustrated arrangement are linear so as to traverse between opposite ends 45A, 45B thereof a linear path along the interior of the drum 25, extend in a downstream axial direction directed from the upstream drum end 29 towards the downstream drum end 34 and angularly in an opposite direction to a prescribed direction of rotation of the drum around the axis R, so as to form a ramped surface to push or displace the fuel in the downstream axial direction of the drum 25 when the drum is rotated. In the illustrated arrangement, each of the flights 44 individually extends only a partial length or depth of the combustion portion 26; however, collectively, the flights 44 span the full length of the combustion portion 26.

In contrast to the combustion portion 26, the peripheral wall 39 of the drum's drive portion 28 is imperforate, as it is not desired to support combustion in the drive portion. Furthermore, the drive portion 28 is sized diametrically smaller than the combustion portion 26 to correspond in diameter to a fuel feeding system 46 of the furnace and burner, which will be described in further detail later.

The drum sections of different diameter, which are in direct communication with one another, are interconnected by an annular wall 47 which lies in a transverse plane to the rotational axis R. In the illustrated arrangement, the wall 47, which is at an intermediary location of the drum's length between opposite ends 29 and 34, is perpendicularly transverse or normal to the axis R and spans radially between the peripheral walls 38 and 39 of the combustion and drive portion 26, 28.

To structurally reinforce the drum 25 at a joint defined at wall 47 between the two diametrically differently sized sections of drum 26 and 28, the peripheral wall 38 of the combustion portion extends upstream of the joint 47 to provide a mounting location for another annular or disk-like wall 50 radially spanning between the peripheral walls 38, 39. However, this extension of the combustion portion's peripheral wall 38 does not locate the same kind of distributed openings 41, since fuel is not collected or contained in the space between walls 47 and 50.

Further to the different diameters, the two portions of the drum 25 are distinguished or differentiated in that the drive portion 28, that is its peripheral wall 39, is circular cylindrical in shape, and the combustion portion 26, that is its peripheral wall 38, is polygonal cylindrical in shape. That is, the combustion portion 26 has a cross-section comprising a plurality of linear segments instead of a continuous circular arc.

To rotationally support the drum without substantially inhibiting or impeding admittance of oxygen to the interior thereof through the openings 41, the drum 25 is rotatably supported at or adjacent each of the external or upstream end 29 and the downstream end 34 and is free of rotational support therebetween. Since the drum's combustion portion 26 is polygonal cylindrical in shape, the drum 25 comprises one or more axially-outwardly projecting annular flanges 53 supported on an outer side 38B the peripheral wall of the combustion portion at or adjacent the downstream end 34 of the drum, and there are provided a plurality of rollers 55 rotatably supported in the burner housing 22 and arranged for rolling engagement with the annular flanges 53 at circumferentially spaced positions of the drum. In the illustrated arrangement, there are plural flanges 53 at axially spaced position of the drum, arranged in a group adjacent the downstream drum end 34. Outer peripheries 53A of the flanges 53 collectively define a circular cylindrical bearing surface of the drum disposed generally at the downstream drum end for rotational support thereat.

In the illustrated arrangement, the rollers 55 are rotatably supported at horizontally opposite locations at an inner surface 57 of the peripheral housing wall 24B, such that the rollers 55 are in rolling engagement with the drum at lower quadrants thereof. Axes 59 of the rollers 55 are oriented substantially parallel to the rotational axis R of the drum.

In conjunction with the foregoing generally at the downstream end 34, the drum's drive portion 28, which defines the upstream end 29, is received in a bushing 62 supported by the housing. The bushing 62 is stationary and is supported by the burner housing 22 at the primary panel 24A. Since the drive portion 28 projects from the burner housing 22, the bushing 62 rotatably supports the drive portion 28 at an intermediary location thereon, but closer to the upstream end 29 than to an opposite end 63 thereof at the joint of the drum 47, which is a downstream end of the drive portion.

In the illustrated arrangement, the bushing 62 is configured to receive the peripheral wall 39 of the drive portion in snug or intimate relation. In a small circumferential gap which exists therebetween, the bushing 62 is configured to receive a lubricant to reduce friction in relative rotational movement between the stationary bushing 62 and the rotatable drive portion 28.

In further regard to construction of the combustion portion 26, the peripheral wall 38 of the combustion portion 26 comprises an outer metallic wall 64 and an inner wall 65 of refractory material. As more clearly shown in FIG. 10 , the inner wall 65 of refractory material comprises a plurality of axially-extending sections 68 arranged side-by-side in a circumferential direction of the drum. Thus, the outer wall 64 acts as a substrate or base for mounting the refractory sections 65 thereto to line an interior of the combustion portion. Since the combustion portion 26 is polygonal cylindrical in shape, the refractory sections 68 are substantially trapezoidal in cross-section so as to be tapered from their outer faces which are mounted in butting engagement with the outer wall 64 to their inner faces defining an interior surface of the combustion portion at the inner side 38A.

In the illustrated arrangement, the whole interior of the combustion portion 26 is lined with refractory material 65. As such, further to lining the peripheral wall 38, the wall 47 has refractory material 70 thereon, too. The refractory material 70 is in the form of a disc to cover an interior surface of the wall 47.

In contrast to the dual-construction of the combustion portion 26, the peripheral wall 39 of the drive portion 28 comprises a single body which is metallic. This single body defines the peripheral wall 39, which is imperforate, circular cylindrical in shape, and has a smooth outer surface to provide a smooth, uninterrupted cylindrical bearing surface for rotation within the stationary bushing 62.

Referring back to FIGS. 7 and 9 , to feed the fuel to be combusted in the drum's combustion portion 26, there is provided the fuel feeding system 46 with a screw conveyor 74 in coaxial alignment with the drum 25. The screw conveyor 74 comprises a shaft 76, a housing 77 in the form of a conduit in which the shaft is rotatably supported, and helical flighting 79 carried on the shaft to displace particulate material in an axial direction along the conveyor housing.

In the illustrated arrangement, the helical flighting 79 of the screw conveyor 74 extends into the drive portion 28 to displace the fuel to the combustion portion 26. The flighting 79 passes through the opening of the external end 29 and extends into the drive portion 29 over a partial but majority depth thereof. As such, a downstream end 79A of the flighting is spaced from a downstream end 63 of the drive portion at the joint between the combustion and drive portions, which is registered with the wall 47.

In this arrangement, the drive portion 28 of the drum, which is sized diametrically smaller than the combustion portion 26, is sized diametrically substantially equal to the flighting 79 of the screw conveyor 74 to snugly or intimately receive the same. In other words, an inner diameter of the peripheral wall 39 of the drive portion 28 is slightly larger than an outer diameter of the flighting 79. Thus, the conveyor flighting 79 which spans substantially a full diameter of the drive portion 28 can be effective at pushing the particulate fuel through the drive portion 28 to dispense same to the combustion portion 26.

The fuel feeding system 46 includes a motor and transmission to drive rotation of the screw conveyor, and an air-lock to prevent combustion of fuel upstream from the screw conveyor 74.

To rotate the drum, the external drive system 31 is operatively coupled to the drive portion 28 by a sprocket 86 supported at or adjacent the external, upstream end 29 of the drum. The drive system 31 comprising a motor and a transmission is disposed in axially offset relation to the drum's rotational axis R in view of the coaxial feed system 46.

This arrangement acts to displace and agitate fuel under combustion, which is helpful to prevent clumping thereof and to clean the burn chamber. Thus, the furnace burner 20 is suited for use with various solid particulate fuels.

In use, solid particulate fuel is fed into the burn chamber 7 coaxially of the drum 25. Preferably, a conveying member, which in the illustrated arrangement is in the form of screw conveyor, acts to displace the fuel over an initial upstream depth of the drum, in order to deliver the fuel to the combustion portion 26 of the drum, which is disposed at an inwardly spaced location from an exterior housing of the furnace 1.

Once the fuel has been delivered to the combustion portion 26 of the drum, the fuel is ignited in the presence of oxygen admitted to an interior of the combustion portion 26 via openings 41. The fuel can be ignited manually, by access to the burn chamber through the furnace housing 4, or automatically by an ignition system configured to generate heat for igniting the fuel inside the drum's combustion portion 26.

After ignition and during combustion, and even during feeding, the drum is rotate in a single, prescribed rotational direction, such that the flights 44 in the combustion portion act to agitate and displace fuel upon rotation of the drum.

The exhaust gas of combustion that is generated inside the combustion portion 26 of the drum is guided out through the open downstream end 34 by the airflow generated in the furnace, such that the exhaust gas is passed through the heat exchanger to extract heat therefrom and eventually to the flue for release to the environment.

As the fuel is consumed during combustion, the drum flights 44 act to displace the fuel towards the downstream end 34 of the drum, which is open to release the consumed fuel for removal to waste by the ash removal system of the furnace.

As described hereinbefore, the present invention relates to a burn chamber that can be used for multiple fuel types. Once the fuel has been delivered, a rotating drum moves forward, flips and breaks up any clusters of fuel, and prevents fuels from clumping, sticking and melting together. The process in which the fuels are broken up allows air to surround the fuel, allowing for near complete combustion. The surrounding air chamber introduces air from all sides which enables combustion of a variety of fuels. The burn chamber is lined with refractory bricks that have flighting incorporated into them. The flighting in the drum slowly moves the fuel as it burns, at the end of the burn chamber the fuel is burned up and gets dropped into the ash box where it eventually gets removed. The constant turning of the drum helps reduce large chunks and pieces which usually create a problem in other style burners.

As described hereinbefore, the present invention also relates to a furnace burner for combusting solid particulate fuel comprises a drum configured for containing the solid particulate fuel for combustion. The drum is supported in a burn chamber of a furnace for rotation about a substantially horizontal axis. The drum comprises a combustion portion inside the burn chamber and configured to support combustion of the fuel therein and a drive portion connected to the combustion portion and extending therefrom to an external end disposed outside the burn chamber for operative coupling to a drive system to rotate the drum. The combustion portion is perforated to permit passage of air but not fuel through a peripheral wall of the combustion portion, and comprises one or more interior flights extending axially and angularly of the drum in a manner conducive of movement of the particulate fuel, upon rotation of the drum, towards a downstream end to release fuel consumed during combustion.

The scope of the claims should not be limited by the preferred embodiments set forth in the examples but should be given the broadest interpretation consistent with the specification as a whole. 

1. A furnace burner for combusting solid particulate fuel, comprising: a housing defining a burn chamber arranged for receiving the solid particulate fuel for combustion thereof to generate exhaust gas; a drum supported in the burn chamber and configured for containing the solid particulate fuel for combustion, wherein the drum is supported for rotation about a substantially horizontal axis; wherein the drum comprises a combustion portion inside the burn chamber and configured to support combustion of the fuel therein and a drive portion connected to the combustion portion and extending therefrom to an external end disposed outside the burn chamber, wherein the drive portion is arranged for operative coupling to a drive system configured to rotate the drum around the axis; wherein the drum extends axially from the external end configured to receive the fuel to a downstream end configured to release the fuel that has substantially combusted for disposal to waste; wherein each of the combustion portion and the drive portion of the drum comprises a tubular peripheral wall encompassing the axis, wherein the peripheral wall of the combustion portion locates a plurality of openings configured to permit passage of air but not the solid particulate fuel therethrough; and wherein the combustion portion comprises one or more flights disposed on an inner side of the peripheral wall, wherein the one or more flights extend axially and angularly of the drum in a manner conducive of movement of the solid particulate fuel towards the downstream end upon rotation of the drum.
 2. The furnace burner of claim 1 wherein the openings in the peripheral wall of the combustion portion are distributed across the full circumference thereof.
 3. The furnace burner of claim 1 wherein the peripheral wall of the drive portion is imperforate.
 4. The furnace burner of claim 1 wherein the drive portion is sized diametrically smaller than the combustion portion.
 5. The furnace burner of claim 1 wherein the drive portion is circular cylindrical in shape and the combustion portion is polygonal cylindrical in shape.
 6. The furnace burner of claim 1 wherein the drum is rotatably supported at or adjacent each of the external and downstream ends and is free of rotational support therebetween.
 7. The furnace burner of claim 6 wherein, when the combustion portion is polygonal cylindrical in shape, the drum comprises one or more axially-outwardly projecting annular flanges supported on an outer side the peripheral wall of the combustion portion at or adjacent the downstream end of the drum, and the furnace burner further includes a plurality of rollers rotatably supported in the housing and arranged for rolling engagement with the one or more annular flanges at circumferentially spaced positions of the drum.
 8. The furnace burner of claim 6 wherein the drive portion of the drum is received in a bushing supported by the housing.
 9. The furnace burner of claim 1, in combination with a fuel feeding system including a screw conveyor in coaxial alignment with the drum, and the screw conveyor comprises helical flighting, wherein the helical flighting extends into the drive portion.
 10. The furnace burner of claim 1 wherein the housing is configured to provide an air gap around a full circumference of the drum.
 11. The furnace burner of claim 1 wherein the peripheral wall of the combustion portion comprises an outer metallic wall and an inner wall of refractory material, wherein the inner wall of refractory material comprises a plurality of axially-extending sections arranged side-by-side in a circumferential direction of the drum.
 12. A furnace for generating heat from combustion of solid particulate fuel, comprising: a base arranged for resting on a support surface; a housing supported on the base; a burn chamber in the housing and arranged for receiving the solid particulate fuel for combustion thereof to generate exhaust gas; an inlet in the housing in fluidic communication with the burn chamber and configured for admitting air from an ambient environment of the furnace into the burn chamber for the combustion of the solid particulate fuel; a heat exchanger supported in the housing outside the burn chamber and in fluidic communication therewith to receive the exhaust gas therefrom, wherein the heat exchanger is configured for transferring heat from the exhaust gas to a heating medium which acts to distribute the heat; a flue in fluidic communication with the heat exchanger and arranged for releasing the exhaust gas with the heat removed therefrom to the ambient environment of the furnace; a fan operatively carried by the housing at a spaced location from the burn chamber and arranged to generate an airflow to draw gas from the burn chamber and to the flue so as to define a flow of gas through the furnace; and a burner configured for combusting the solid particulate fuel, wherein the burner comprises: a drum supported in the burn chamber and configured for containing the solid particulate fuel for combustion, wherein the drum is supported for rotation about a substantially horizontal axis; wherein the drum comprises a combustion portion inside the burn chamber and configured to support combustion of the fuel therein and a drive portion connected to the combustion portion and extending therefrom to an external end disposed outside the burn chamber, wherein the drive portion is arranged for operative coupling to a drive system configured to rotate the drum around the axis; wherein the drum extends axially from the external end configured to receive the fuel to a downstream end configured to release the fuel that has substantially combusted for disposal to waste; wherein each of the combustion portion and the drive portion of the drum comprises a tubular peripheral wall encompassing the axis, wherein the peripheral wall of the combustion portion locates a plurality of openings configured to permit passage of air but not the solid particulate fuel therethrough; and wherein the combustion portion comprises one or more flights disposed on an inner side of the peripheral wall, wherein the one or more flights extend axially and angularly of the drum in a manner conducive of movement of the solid particulate fuel towards the downstream end upon rotation of the drum. 